Cellular phones available mainly across Europe have already been designed by encasing in cellular phone cases a plug-in form of subscriber identity modules (abbreviated as SIMs) with IC chips having programs to make cellular phone's function implementable. In more recent years, however, universal subscriber identity modules (hereinafter referred to as USIMs for short) designed to enable the SIMs to be utilized all over the world have been under consideration.
Conventional cellular phone systems, by the way, are merely allowed to register therein an application program in a single language; when USIMs having interpreters in varying languages are co-resident and available for each user, it is impossible to download programs to all users via cellular phone systems. Never until now is there any solution to this problem.
Having been made to solve the aforesaid problem, the present invention has for its object to enable programs to be downloaded through cellular phone systems with high security, even when USIMs having interpreters of varying program specifications are co-resident and available for each user.